Traditionally, most kinds of paper clips are made of steel wires. It is very convenient for clipping documents and especially for papers. Referring to FIG. 1, which is the 3-dimension view of prior art and normally made of plastic, because plastic is a flexible material. A bottom surface of paper 4 is put on first clipping piece 1, and second clipping piece 2 is above a top surface of paper 4, which means paper 4 is within the first clipping piece 1 and the second clipping paper 2. Top edge 40 is against to joint place 3, thus the paper 4 can be clamped tightly. The first clipping piece 1 and the second clipping piece 2 are located at the same horizontal plane, which means joint place 3 is no height difference. Therefore, this type of paper clip as in FIG. 1 is just suitable for thin thickness of document, such as one paper or only a couple of papers; on the other hand, a thick document is not tightly clamped.
Referring to FIG. 2, which is another 3-dimension view of prior art. This is an advance type of clip. First clipping piece 5 and second clipping piece 6 are not on the same horizontal plane, and support beam 7 is with a height, therefore the height has a capacity for thicker (documents, but the prior art cannot be tightly enough to clamp one piece of paper, because touching line 8 of the first clipping piece 5 and the second clipping piece 6 is formed as a line, thus the clamping force is not strong enough.
Referring to FIG. 3, which is the third 3-dimension view of prior art and the oldest but the most convenient prior art, so the shortcomings of the types in FIGS. 1 and 2 are all included in the prior art. Which means that first clipping piece 9 and second clipping piece 10 are at the same horizontal plane, so the prior art is not suitable for thicker documents as well; further, the prior art is made of steel wire as usual, thus the application force for clamping is as two individual lines, so the application condition is just same as the prior art in FIG. 2. Therefore, the prior arts as mentioned above are not good enough to manage the present paper work operations.
U.S. Pat. No. 3,950,823 discloses a tie clasp which is formed from a single sheet of spring metal and comprises primary a base portion and a spring clip portion. The spring clip portion is formed at one end of the base portion and has a curved resilient section area and a free end section area. The base portion is provided with a slot. The central section of the spring clip portion extends inwardly into the slot. The curved resilient section area connects the base portion and the spring clip portion and has the same width as the spring clip portion. The free end section area of the spring clip portion extends out of the front end of the base portion in such a manner that the free end section area of spring clip portion overlaps the front end of base portion in the projection of top view. In addition, the curved resilient section area of the spring clip portion also overlaps the rear end of base portion in the projection of top view. In order to provide sufficient structural strength, the right end of the slot must be apart from the bottom side of the curved resilient section area so as to leave a sufficient width thereof. Such kind of structure makes the tie clasp of U.S. Pat. No. 3,950,823 difficult to be manufactured by plastic ejection, since the overlapped portions of the tie clasp makes it extremely difficult to be taken off from the molds along the top-view direction during the plastic ejecting process. As the result, the tie clasp of U.S. Pat. No. 3,950,823 suffers the deficiency of being difficult to be made by plastic ejection.
U.S. Pat. No. 5,056,748 discloses a molded plastic holder for printed material. The molded plastic holder includes a support panel, curved clip, stiffening rib, open area and mounting holes. The support panel and curved clip are connected at the bottom edge of the curved clip, such that the connecting portion of the bottom edge has exactly the same width as the curved clip. Because the open area is wider than the curved clip, therefore the support panel must has a back portion extending backward from the connected bottom edge in order to provide sufficient structural strength. If this back portion is not large enough, then the effective connection between the support panel and the curved clip will be only at the two ends of the bottom edge and will be prone to break easily. However, since the large back portion is extending in the same plane as the support panel which is substantially perpendicular to the curved concave inner surface of the curved clip, therefore, the back portion of the support panel will extend out of the outer contour of documents which are received and held by the molded plastic holder. In addition, because the curved concave inner surface is the surface where the leading edges of documents will contact, therefore, when lots of documents are received by the holder in the same time, the leading edges of documents tend to become a curved shape in the side view. The leading edges of documents cannot be stacked straightly. Thus the appearance of the holder would be ugly when holding documents.
U.S. Pat. No. 6,254,136 discloses a page holder which includes a spring clip integrally formed with a base. The spring clip has a cavity with substantially parallel edges, an end edge and a curved edge. A tongue is connected to the spring clip at the end edge of the cavity by a connecting member. Similar to the previously described prior art U.S. Pat. No. 5,056,748, the connecting member of U.S. Pat. No. 6,254,136 has a width exactly the same as the tongue. That means, the base of the page holder shown in U.S. Pat. No. 6,254,136 must have a large back portion extending backward from the end edge of cavity. It is impossible to make the base with a back edge being flush with the end edge of the cavity, otherwise the effective connection between the tongue and the base will be only at the two ends of the end edge of the cavity and will be easy to break.
U.S. Pat. No. 5,704,724 discloses a paper clip which is in a flat plane structure. The amount of documents which this paper clip can hold is thus limited. The paper clip disclosed by U.S. Pat. No. 5,704,724 is not suitable for holding lots of documents with significant thickness.
Other conventional clip-like structure, such like the ones illustrated by U.S. Pat. No. 5,113,554, DT 2432880, GE 2254291, and etc., all have similar draw backs as which of the U.S. Pat. No. 5,056,748 and U.S. Pat. No. 6,254,136. That is, all of the conventional clip-like structures include a “tongue” and a “base” and a “connecting member” for connecting the “tongue” and “base”. And, the most important thing is, the “connecting member” of these prior arts is always having a width exactly the same as the “tongue”, which consequently results in the “base” must have a “back side portion” which extends backward from the “tongue” and cannot lie on the same vertical plane as the “connecting member”. As a result, when the clip-like structure of prior art is holding something such like documents, the so called “back side portion” of the “base” will definitely protrude out of the outer contour of the documents. It fails to provide an integral and beautiful appearance to the clip and the documents.
It is notable that, for a clip-like structure like the ones previously described, there are always four primary elements being comprised, namely “tongue”, “base”, “connecting member” and “slot” located on the “base”. In order to provide sufficient structural strength, there must be sufficient thickness or width near the bottom of the “connecting member”. For example, for the clip-like structures shown in U.S. Pat. No. 5,113,554 and U.S. Pat. No. 3,950,823, their “slot” does not extend to contact with the “connecting member”, such that a sufficient width is formed between the “slot” and the “connecting member” to provide the structural strength required. In the other hand, for the clip-like structures shown in U.S. Pat. No. 5,056,748, U.S. Pat. No. 6,254,136, DT 2432880 and GB 2254291, a “back side portion” of the “base” is formed behind the “connecting member” for providing sufficient width for the connection between the “base” and “connecting member”, such that the structural strength thereof would meet the needs.